1. Field of the Invention
The invention relates to a gas-heated heat exchanger with a pipe feeding heating gas, where the wall of the pipe is interspersed by at least a longitudinally running bundle of gas exit nozzles.
2. Description of the Related Art including information disclosed under 37 CRF .sctn..sctn. 1.97-1.99
It is known that the nitrogen oxide (NO.sub.x) contents of exhaust gases can be influenced by changing three essential parameters, that is, of temperature, partial pressure of oxygen, and time.
It is further known that the height and distribution of the temperature can be controlled by cooling of the burner chamber walls or the burner plate.
However, if one considers the temperatures within the individual flame, then it can be recognized that the maximum temperature is located neither at the base of the flame nor, in case of multi-flame burners, at the edge of a flame zone, but is located in each case within the upper third of each individual flame.
Rods made of a refractory or thermally stable material can be positioned such at the burner next to the burner flames that they deflect the heat for a temperature balancing from the hot zones into cooler regions.
In fact, this achieves a decrease in the nitrogen oxide (NO.sub.x) content of the exhaust gases, but in case of cramped space situations, the flames are disturbed such that the carbon monoxide (CO) emission increases. The rods should be provided at a larger distance from the flames, whereby, in fact, the carbon monoxide content would be reduced but the nitrogen oxide content would increase.